The soot particle size distribution in premixed flames of the light and heavy distillate fraction of gasoline was measured. The results were also compared with particles yielding from the not-distilled gasoline to study the difference in soot formation tendency between the practical fuel and its distillates. It was observed that the particle size distribution from the light and heavy distillates was similar with that of gasoline in a qualitative level, showing typical unimodal and bimodal distribution. Also, the heavy distillate had much higher particle growth rate than the light distillate, and those of gasoline were between the two distillates. However, the particle nucleation strength in premixed gasoline flames was higher than that in flames of either distillate and this also caused a higher particle number density, demonstrating that a synergistic effect on particle nucleation existed between the light and heavy distillate fractions. (C) 2019 The Combustion Institute. Published by Elsevier Inc. All rights reserved.